// By default EventEmitters will print a warning if more than
// 10 listeners are added to it. This is a useful default which
// helps finding memory leaks.
//
// Obviously not all Emitters should be limited to 10. This function allows
// that to be increased. Set to zero for unlimited.
var isArray = Array.isArray;
var defaultMaxListeners = 10;
class EventEmitter extends cc.Component {
    _events;
    _maxListeners;
    domain;
    setMaxListeners(n) {
        if (!this._events) this._events = {};
        this._maxListeners = n;
    }
    emit(...arg) {
        var type = arguments[0];
        // If there is no 'error' event listener then throw.
        if (type === 'error') {
          if (!this._events || !this._events.error ||
            (isArray(this._events.error) && !this._events.error.length)) {
            if (this.domain) {
              var er = arguments[1];
              er.domain_emitter = this;
              er.domain = this.domain;
              er.domain_thrown = false;
              this.domain.emit('error', er);
              return false;
            }
      
            if (arguments[1] instanceof Error) {
              throw arguments[1]; // Unhandled 'error' event
            } else {
              throw new Error("Uncaught, unspecified 'error' event.");
            }
            return false;
          }
        }
      
        if (!this._events) return false;
        var handler = this._events[type];
        if (!handler) return false;
      
        if (typeof handler == 'function') {
          if (this.domain) {
            this.domain.enter();
          }
          switch (arguments.length) {
            // fast cases
            case 1:
              handler.call(this);
              break;
            case 2:
              handler.call(this, arguments[1]);
              break;
            case 3:
              handler.call(this, arguments[1], arguments[2]);
              break;
            // slower
            default:
              var l = arguments.length;
              var args = new Array(l - 1);
              for (var i = 1; i < l; i++) args[i - 1] = arguments[i];
              handler.apply(this, args);
          }
          if (this.domain) {
            this.domain.exit();
          }
          return true;
      
        } else if (isArray(handler)) {
          if (this.domain) {
            this.domain.enter();
          }
          var l = arguments.length;
          var args = new Array(l - 1);
          for (var i = 1; i < l; i++) args[i - 1] = arguments[i];
      
          var listeners = handler.slice();
          for (var i = 0, l = listeners.length; i < l; i++) {
            listeners[i].apply(this, args);
          }
          if (this.domain) {
            this.domain.exit();
          }
          return true;
      
        } else {
          return false;
        }
    }
    addListener (type, listener) {
        if ('function' !== typeof listener) {
          throw new Error('addListener only takes instances of Function');
        }
      
        if (!this._events) this._events = {};
      
        // To avoid recursion in the case that type == "newListeners"! Before
        // adding it to the listeners, first emit "newListeners".
        this.emit('newListener', type, typeof listener.listener === 'function' ? listener.listener : listener);
      
        if (!this._events[type]) {
          // Optimize the case of one listener. Don't need the extra array object.
          this._events[type] = listener;
        } else if (isArray(this._events[type])) {
      
          // If we've already got an array, just append.
          this._events[type].push(listener);
      
        } else {
          // Adding the second element, need to change to array.
          this._events[type] = [this._events[type], listener];
      
        }
      
        // Check for listener leak
        if (isArray(this._events[type]) && !this._events[type].warned) {
          var m;
          if (this._maxListeners !== undefined) {
            m = this._maxListeners;
          } else {
            m = defaultMaxListeners;
          }
      
          if (m && m > 0 && this._events[type].length > m) {
            this._events[type].warned = true;
            console.error('(node) warning: possible EventEmitter memory ' +
              'leak detected. %d listeners added. ' +
              'Use emitter.setMaxListeners() to increase limit.',
              this._events[type].length);
            console.trace();
          }
        }
      
        return this;
    }
    once(type, listener) {
        if ('function' !== typeof listener) {
          throw new Error('.once only takes instances of Function');
        }
      
        var self = this;
        function g() {
          self.removeListener(type, g);
          listener.apply(this, arguments);
        };
      
        g.listener = listener;
        self.on(type, g);
      
        return this;
    };
    removeListener(type, listener) {
        if ('function' !== typeof listener) {
          throw new Error('removeListener only takes instances of Function');
        }
      
        // does not use listeners(), so no side effect of creating _events[type]
        if (!this._events || !this._events[type]) return this;
      
        var list = this._events[type];
      
        if (isArray(list)) {
          var position = -1;
          for (var i = 0, length = list.length; i < length; i++) {
            if (list[i] === listener ||
              (list[i].listener && list[i].listener === listener)) {
              position = i;
              break;
            }
          }
      
          if (position < 0) return this;
          list.splice(position, 1);
        } else if (list === listener ||
          (list.listener && list.listener === listener)) {
          delete this._events[type];
        }
        return this;
    }
    removeAllListeners = function (type) {
        if (arguments.length === 0) {
            this._events = {};
            return this;
        }
        
        var events = this._events && this._events[type];
        if (!events) return this;
        
        if (isArray(events)) {
            events.splice(0);
        } else {
            this._events[type] = null;
        }
        
        return this;
    }
    listeners = function (type) {
        if (!this._events) this._events = {};
        if (!this._events[type]) this._events[type] = [];
        if (!isArray(this._events[type])) {
            this._events[type] = [this._events[type]];
        }
        return this._events[type];
    }
    on(ev, cb) {
        this.addListener(ev, cb);
    }
}

export default EventEmitter;
